Dynamo-electric machinery.



No. 775,458. PATENTED NOV. 22, 1904.

,, Hre. REIST.

DYNAMO ELECTRIC MACHINERY.

APPLICATION FILED MAY 9, 1902.

N0 MODEL. 2 SHEETS-SHBET 1.

0 Hem" QReisC.

No 775,458. PATENTED NOV. 22, 1904. H. G. REIST.

DYNAMO ELECTRIC MACHINERY.

APPLICATION FILED MAY 9, 1902. 7

no MODEL. 2 SHEETS-SHEET 2.

CJrCncsscs: lnventor'z' Henr GReiSG. v r v P b wob UNITED STATESPatented November 22, 1904.

PATENT OFETcE.

HENRY G. REIST, OF SOHENEOTADY, NEW YORK, ASSIGN OR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

, DYNAMO-ELECTRIC MACHINERY.

SPECIFICATION forming part of Letters Patent No. 775,458, dated November22, 1904.

Application filed May 9, 1902. Serial No. 106,573. (No model.)

To all whom it may concern;

Be it known that I, HENRY G. REIs'r, a citizen of the United States,residing at Schenec tady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements inDynamo-ElectricMachinery, of which the following is a specification.

My present invention relates to certain improvements in the constructionand mounting of dynamo-electric machines, the novel fea-' tures of whichare particularly pointed out in the appended claims.

The invention is capable of various applications, but is hereinafter setforth, for purposesof illustration, in connection with-an exciter for adynamo-electric machine of that type now commonly known in the art as acompensated alternator, wherein current from the alternator is conveyedeither directly or inductively to the exciter-armature, which currentthus conveyed operates to vary thearmature reaction of the exciter insuch manneras to compensate for variations of the load and power factorof the main generator or alternator.

In the drawings I have not considered it necessary to illustrate themain alternator, but have shown merely one of its main bearings orpillow-blocks, in connection with which the exciter for the alternatoris mounted.

Figure 1 is a view, partly in section, of an exciter arranged inaccordancewith my invention on one of the pillow-blocks of the mainalternator, not shown. Fig. 2 is adetail, and Fig. 3 is an end view, ofso much of the machine as is represented in Fig. 1. Fig. 4 is anelevation of a pole-piece laminae.

In Fig. 1 the pillow-block of the main alternator is represented at 1and the main shaft carried by the pillow-block at 2, this shaft beingrepresented in end view at 2 in Fig. 3. The pillow-block is formed witha circular opening directly below the main bearing, and in this openingis mounted a hollow cylinder or sleeve 3, which is cast integral withbut eccentric to the ring-shaped supporting frame or yoke 1 of theexciter, (represented generally at 5.) Radial arms, such as 6 and 7,serve to connect the sleeve'3 with the ring-like memis represented at11.

main machine.

-and'is separable from the sleeve 3 and is held in position by bolts orother securing means, one of which bolts is represented at 10. Thesupport for the other or outer bearing of the shaft 8 is formed integralwith the sleeve 3 and Theexciter-shaft carries a pinion 12, which mesheswith a drivinggear 13, mounted on the main shaft 2 of the The pinion isinclosed within the casing supporting the exciter-shaft, while 5 thedriving-gear 13 is similarly inclosed by means of agear-casing 14.

To enable the driving-gear and its pinion to be adjusted relatively toeach other, the

cylinder 3 is cast so that its axis is displaced 7c.

laterally from the axis of the shaft '8, which latter axis of course iscentral with respect to the ring-shaped field magnet support or yoke 4.This is represented perhaps best in Fig. 2, in which a bounding-line 15represents the circumference of the flange 16 formed on the cylinder 3.The dotted circle 17, displaced eccentrically with respect to thecircumference 15, represents the outer surface of the cylinder 3, whilethe small circle 18, concentric with the circumference 15, indicates theshaft 8, which,

as will be seen, is of course eccentric with respect to the axis of thecylinder 3. If this cylinder be rotated slightly in its bearings, it

is obvious that the shaft 8 will rise or fall in 5 space, as the casemay be, thereby permitting the pinion 12, carried by the shaft, to beadjusted to or from the driving-gear 13 by the adjusting-screws 19,asmay be required. After suitable adjustment is secured the mov- 9 ablestructure, including the sleeve 3 and parts carried thereby, is clampedin place by means of set-screws 19.

The'ring-shaped member 4 forms the mechanical support for thefield-magnet structure proper of the exciter, this structure consistingof a ring 20, provided with a number of pole-pieces upon which aremounted the usual field-coils, as indicated at 21 in Fig. The pole-facesof the pole-piece are joined by a ring of magnetic material 21 in orderto secure a somewhat more uniform transition of flux about the surfaceof the exciter-armature. The ring or yoke 20, carrying the polepieces,is adjusted within its supporting member at so as to enable thepole-pieces to be adjusted around the exciter armature, for purposeswell understood in connection with this class of machine. To secure thisadjustment conveniently, a lug 21, connected to the yoke 20, extendsdownward and is arranged to engage adjusting-mits 22 23 on ascrewthreaded rod 241-, secured at one end to the supporting-trame 4. Bysuitably adjusting these nuts in an obvious manner the lield structureof the exciter may be adjusted about the exciter-armature.

The lnush-holders 25 to 28 are arranged so that those of like polarityare supported from a brush-holder yoke formed of a somewhat bow-shapedpiece of metal, such as at 29 or 30. Each brush-holder yoke ismechanically secured to but insulated from a ring 31, movable within thelield-frame 4, and serves the double function of a mechanical supportfor and electrical connection between brush-holders of like polarity.

The il'nportant feature of my invention consists in a means for securingstable operation of dynamo-electric machines such, for example, as theexciter above described. The exciter referred to is required by reasonof its relations to the main alternator to vary in voltage and fieldstrength through very wide limits. in the ordinary construction of eX-citer the design is generally such as to make the machine work upon thatportion of the saturation curve above or near the knee or bend where theiron commences to saturate. \Vithin and above this range the field fluxdoes not respond proportionally to variation of voltage at the terminalsof the field-winding. By reason of this fact variations of voltagegenerated in the armature are not exaggerated by resultant variations ofstrength of field, thereby insuring a stability of operation ascontrasted with wide and erratic fluctuations of voltage, such as wouldoccur if the machine were worked upon a portion of its magneticcharacteristic below the bend. In accordance with my invention thecharacteristic curve of the machine is shaped so as to secure stabilityof operation throughout a range varying from comparatively low lieldstrength up to magnetization approaching saturation. To secure thisstable operation over the low field densities, I shape the magneticcircuit or circuits of the machine so that a portion of the samecommences to saturate with low values of total flux, and with risingvalues of flux lines of force are shunted across a small air-gap in themagnetic circuit, thereby producing a further drooping of the magneticcharacteristic.

Heretofore it has been proposed to utilize a constricted neck in themagnetic circuit in connection with an air-gap, the neck being ofsubstantially the same length as the air-gap. Under these circumstancesthe reluctance of the neck formed such a small portion of the reluctanceof the entire magnetic circuit that no appreciable cflect was producedupon the saturation curve until the neck reached saturation. Bylengthening the neck, however, the saturation curve begins to bendalmost as soon as it leaves the origin, and when this neck or restrictedpath for the magnetic flux becomes saturated the air-gap is then broughtinto operation. The result is a saturation curve permitting a wide rangeof stable operation for the exciter.

In Fig. 1 is shown one mode of arranging the magnetic circuit to producethe result specified, while Fig. 4: represents a different arrangementfor producing the same general results. In Fig. 1 each field-pole isslotted, so as to form two constricted necks 31 and 32, and theseconstricted portions project slightly beyond the level of the portion 53of the pole lying between the slots. The cylindrical band of soft ironindicated at 21 and shown in side elevation in Fig. 3 connects togetherthe projecting portions of all of the poles, whereby a more gradualtransition of flux about the surface of the armature is obtained.Inasmuch, however, as the central portion 33 of each pole does notextend quite out to a line joining the surfaces of the constrictedportions or necks 31 32,it will be seen that a slot is formed betweenthe portion 33 and the cylindrical ring 21. The arrangementv shown inFig. L is similar in principle though differing slightly inconstruction. In this case the field-pole is provided with an opening35, havlug a cross-section similar to the letter H. The cross-bar 36 ofthe H represents the slot in the magnetic circuit corresponding to theslot between the portions 38 and 21 in Fig. l. The thin connectingportions 37 and 38 of the polepiece in Fig. 4 are of sufiicient length,so that their reluctance may have an appreciable effect upon thereluctance of the entire magnetic circuit. Inasmuch as these begin tosaturate at comparatively low values of the total flux in the magneticcircuit, they have the effect of causing the saturation curve of themagnetic circuit to bend or droop at a lowerfiux value than would be thecase if the length of these portions were equal only to the length ofthe cut or slots 36 in the magnetic circuit. As set forth above,somewhat more in detail, the resulting effect is an extension of therange of stability of operation of the machine, and this, as has beenmentioned, is in many cases an extremely-valuable feature.

Certain features of the construction shown and described, but notclaimed in this case, are claimed in my copending application Serial No.157,556, Which was filed May 18, 1903, as a division of thisapplication.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In a dynamo-electric machine, a magnetic circuit having a portionthereof of constricted cross-section, and a slot in the magnetic circuithaving a Width in the direction of the magnetic flux less than thelength of said portion of the'magnetic circuit of constrictedcross-section.

2. In a dynamo-electric machine, a field magnetlc circult, provlded atone or more portions thereof with tWo paths for the magnetic flux, oneof said paths including a slot I5 in the material forming the magneticcircuit and the other a reduced cross-section of said magnetic materialof a length greater than the Width of said slot.

In Witness whereof I have hereunto set my 20 hand this 7 thday of May,1902.

HENRY G. REIST.

W'itnesses:

BENJAMIN B. HULL, HELEN ORFORD.

